the word wiener is underused (idea)

If you're using any term that means penis as an insult, it's likely that you want a strong, vulgar effect. This is probably why the term "wiener" isn't used much as an insult. It also has an air of elementary school when things were pee-pees and private parts. However, for use on your friends when they're being dumb, the term wiener should indeed be used more often. It would add to the insult to make it silly-sounding.